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How
might high fat diets promote pattern baldness
There is no direct evidence that diet or being overweight contributes
to pattern baldness, but below is one potential mechanism by which
high fat diets might influence baldness in susceptible individuals.
Pattern alopecia is the net result from a complex series of interactions
in the androgen hormone system. However, it has been shown that
hair follicles on top of the scalp in men are more adversely affected
and more likely to miniaturize if there are high levels of free
testosterone in the blood. A high blood testosterone level in turn
is likely to give rise to high dihydrotestosterone (DHT) around
hair follicles which in turn binds to hair follicle cell receptors
causing miniaturization by some as yet unknown mechanism.
Free testosterone in the blood not only relies on how much it is
produced, but also how much of it is bound by a regulating factor
called sex hormone binding globulin (SHBG). The rate of SHBG production
is profoundly influenced by insulin levels and in turn insulin production
is affected by fat. Low fat diets and low fat body weight (you can
be thin and still have a high proportion of fat as your body weight!)
depress insulin production. Depressed insulin production increases
SHBG production.
Women with polycystic ovary syndrome (PCOS) provide some evidence
of a relationship between increased fat, increased insulin, and
consequently increased levels of androgen production. About 50%
of women with PCOS are overweight. Most obese women with PCOS are
insulin resistant and hyperinsulinemic. Moreover, a significant
positive correlation exists between the degree of hyperandrogenism
and that of hyperinsulinism. Insulin is capable of stimulating ovarian
androgen secretion and controlling androgen metabolism and transport
in peripheral tissues. Abdominal body fat distribution in obese
women with PCOS amplifies the degree of hyperandrogenism and related
clinical symptoms and signs. Both loss of body weight and/or the
reduction of the degree of hyperinsulinemia, induced by diet or
insulin-sensitizing drugs, have important effects, since they reduce
blood androgen levels and can improve ovulation and clinical signs
of hyperandrogenism in women with PCOS.
A diet high in fat has been linked to male prostate cancer, possibly
through an influence on SHBG. Studies have shown that diet and exercise
can modify insulin levels, potentially affecting SHBG and the biologically
available levels of androgens. In one study a low fat, high fiber
diet for 27 obese men decreased insulin levels by almost 40% and
SHBG levels increased by about 40%. These changes may be protective
against the development of prostate cancer and potentially against
progression of androgenetic alopecia.
How
might high fat diets promote pattern baldness references
- Pasquali
R, Vicennati V, Gambineri A. [Influence of weight and distribution
of adipose tissue in functional hyperandrogenism]. Contracept
Fertil Sex. 1998 May;26(5):372-5.
- Tymchuk
CN, Tessler SB, Aronson WJ, Barnard RJ. Effects of diet and exercise
on insulin, sex hormone-binding globulin, and prostate-specific
antigen. Nutr Cancer. 1998;31(2):127-31.
- Belanger
A, Locong A, Noel C, Cusan L, Dupont A, Prevost J, Caron S, Sevigny
J. Influence of diet on plasma steroids and sex hormone-binding
globulin levels in adult men. J Steroid Biochem. 1989 Jun;32(6):829-33.
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